1. Field of the Invention
The present invention relates to an air bag apparatus for a passenger seat such as a front passenger seat or a rear passenger seat, and more particularly to an air bag apparatus for a front or rear passenger seat on which a child restraining system (CRS) can be mounted.
2. Description of the Related Art
Some vehicles are provided with an air bag apparatus which protects a passenger sitting in the front passenger seat in case of emergency. Japanese Patent Application Laid-Open No. 2-60858 discloses an example of such an air bag apparatus.
As shown in FIG. 5, in the air bag apparatus for a front passenger seat disclosed in the aforementioned patent publication, an opening 74 for allowing an air bag 76 to expand is formed in a dashboard 70 at a position opposite the chest 72A of a passenger 72. When an inflator is operated by an acceleration sensor during an abrupt deceleration of the vehicle, the air bag 76 expands (or inflates) toward the passenger 72 through the opening 74.
Although such an air bag apparatus is effective when the passenger 72 sitting on the front passenger seat 78 is larger than a predetermined size, i.e., the passenger 72 is an adult, it is not so effective when a child sits in a child restraining system (CRS) mounted on a seat cushion 78A of the front passenger seat 78. Because the child is sufficiently restrained by the CRS which is securely restrained by a webbing of a seat belt system of the vehicle, it may not be necessary to expand the air bag. However, in the conventional air bag apparatus, the air bag expands even when a child is in the seat.
A passenger can be protected even when the conventional air bag apparatus is modified such that a reference value for detecting an abrupt deceleration of the vehicle and expanding the air bag 76 is increased when the webbing has been applied to the passenger as compared to a case in which the webbing has not been applied to the passenger. However, in the conventional air bag apparatus, the air bag expands when the deceleration of the vehicle reaches a preset reference value, whether the webbing has been applied to the passenger 72 or not.
Accordingly, the probability of having to replace air bag apparatuses after traffic accidents becomes high, which unnecessarily increases repair costs.